The present invention relates generally to plant cutting assemblies for use with agricultural harvesters. In particular, the subject application relates to an assembly for preventing debris intrusion and collection within a center knife drive of a harvester. The assembly includes a sealing assembly for an output shaft of the center knife drive and a pressurized air source.
Sickles, typically including cutterbars supporting a row of knives, are used to cut plants including, but not limited to, hay, grasses and small grains. In harvester equipment the knives are constructed as a plurality of knife or sickle sections which are mounted in side-by-side relation forming an elongate metal knife assembly or cutterbar. The knife assembly is normally supported so as to slide longitudinally along an elongate stationary bar that has forwardly projecting, spaced apart guards. The knife assembly moves back and forth in reciprocating motion to move the knives relative to the guards so that the leading knife edges cross over the guards or move through slots in the guards. This motion produces a shearing or cutting action which severs plant stems or stalks or other material that becomes captured between the knives and the guards.
In a harvesting machine such as a combine, a pair of such cutterbars and stationary bars are supported in connection with a cutting head or header and are oriented so as to extend laterally or widthwise along a forward edge portion of structure such as a floor or pan of the header. The floor defines the lower extent of a cut crop or plant flow area, which can include conveying apparatus such as one or more augers or belts. The conveying apparatus is oftentimes operable in cooperation with a harvesting reel for conveying the cut plant material to a feederhouse inlet of the combine.
The pair of cutterbars can be driven by one or two centrally located knife drives which derive their power from power take offs operatively connected to the combine. The knife drives include one or more output shafts that are generally vertically oriented, the reciprocating rotational motion of which are transferred to the cutterbars as a reciprocating lateral motion. A problem with the knife drives is that, because of their location in or below the header floor or pan, the drives are at least partially contained in a relatively low profile or flat housing or cover upon which loose crop material and other undesirable material such as dust, dirt and debris can accumulate. This situation is disadvantageous because, if allowed to accumulate, such material can quickly insulate the drive and reduce dissipation of heat generated by operation of the knife drives. The result can be overheating and premature failure of knife drive components.
In addition, accumulated material can become lodged between the knife drives and the underside of the floor or pan and can even become compacted into a solid mass which limits or prevents upward movement of the knife drive during operation. Likewise, accumulated material can become lodged around the output shafts, which limits or prevents the reciprocating rotational movement of the output shafts. This can be problematic, for instance, if the drive is used with a cutterbar or sickle that can flex upwardly or when the cutterbar is configured to float so as to be movable upwardly toward the header floor or pan. Failure of the cutterbar to flex or move fully upwardly may result in the cutterbar becoming immersed in the soil rather than severing crop close to the ground surface which can result in damage to the cutterbar and/or the knife drive.